挤扩支盘桩的工程应用

介绍了挤扩多支盘桩在工程实例中的应用,并对工程同场地内的挤扩支盘桩与普通钻孔灌注桩进行承载力和沉降的对比试验研究.工程试验结果表明:在同等工程地质条件下,采用挤扩支盘桩能大幅度提高单桩承载力,减少沉降,具有良好的经济效益.     

考虑桩土共同作用的钻孔灌注桩承载性状分析

以盖州北海渔民回迁楼工程为依托,选取其中的C14 号楼为研究对象,对其中两根试桩进行现场静载试验,并获得了Q-S 曲线、侧摩阻力随深度变化曲线、桩身轴力随深度变化曲线及桩土接触面相对位移随深度变化曲线. 然后根据现场勘查资料及有限元参数选取的经验值建立单桩模型,利用大型有限元分析软件ADINA 对单桩进行分析,并根据模拟数据及实测数据利用MATLAB 绘制了各项主要承载特性的对比曲线,一方面验证模型及参数的合理性,另一方面研究桩长对单桩各项主要承载特性的影响. 最后利用单桩验证过的模型及参数建立群桩模型,分析群桩的各项主要承载特性与桩长及桩间距的关系.     

海港大管桩力学性能实验测试与反演研究

利用光纤光栅传感技术,在现场对大管桩在外载作用下的变形情况进行了测试. 根据实验测试结果,利用数值法反分析大管桩力学性能参数,同时得到大管桩接缝处的环氧树脂材料对大管桩整体力学性能影响很小. 反演出的合理的力学性能参数为大管桩的正确受力分析以及健康诊断提供了依据.     

任意段变模量桩纵向振动的解析解

建立了均质土中考虑桩端土和桩侧土作用的任意段变模量桩,讨论了在桩顶受纵向激励时的定解问题,并用拉氏变换(Laplace)求得桩顶速度频域响应的解析解,然后利用卷积定理和拉氏逆变换求得桩顶速度时域响应的解析解,并将其运用到桩基质量的动力检测中.对弹性模量突变桩以及模量连续变化桩的振动特性作了进一步的研究,并将理论曲线与实测曲线进行了拟合对比,结果表明,两者吻合较好.     

单桩动力特性影响因素分析

本文通过对复合平面应变近似法的改进,导出单桩桩基的动力复刚度,分析影响桩基动力刚度和阻尼的因素,得到一些结论,为桩基优化设计提供依据     

非确定信息评价的变权模糊方法

为了将非确定信息定量化,利用三点估计法,确定因素的常权;考虑因素组态对权重的影响,建立因素的变权集;根据区间点估计方法,建立因素的模糊评判矩阵;构造变权的模糊评价模型.应用结果表明,该方法具有科学性和合理性,可为工程非确定性信息评价提供参考.     

控制软土地基上沉井突沉和不均匀下沉的措施

对异型沉井,在软土地基施工时采用水泥搅拌桩加固地基的方法,可以有效防止沉井突沉、不均匀沉隆以及涌土的现象,提供了在软土地基上施工沉井的一种新思路,工艺简便,安全可靠。     

Transfer of Metals from Soil to Crops in an Area near a Coal Gangue Pile in the Guqiao Coal Mine,China

A field survey was conducted to investigate the metal contamination in coal gangue, soils, and crops (rice and soybeans), and to evaluate the possible health risks to the local population through food chain transfer near a coal gangue pile in the Guqiao Coal Mine, China. Contamination levels of zinc, lead, cadmium, and copper in coal gangue, soils, and crops were measured, and bio-accumulation factors from soil to crops were determined; the health risks were calculated accordingly. Results showed that both coal gangue and soil contained high levels of cadmium (0.15 mg kg^?1and 0.20 mg kg^?1) exceeding the background value of the soil. The lead soil concentration was low (9.99 mg kg^?1), but lead in rice (0.38 mg kg^?1) exceeded the maximal permissible limit of 0.2 mg kg^?1. For some tissues of crops studied, there was a significant correlation between the bio-accumulation factor values and the corresponding soil metal concentrations that were best described by a power equation. Oral intake of zinc, cadmium, and copper through crops posed no health risk to local residents, although hazard indices for rice (0.87–2.88) and soybeans (0.06–0.09) suggested that ingestion of rice grains was unsafe for human health. Therefore, rice was inappropriate to be planted in the soil surrounding this coal mine.     

Numerical modeling of free field vibrations due to pile driving using a dynamic soil-structure interaction formulation

This paper presents a numerical model for the prediction of free field vibrations due to vibratory and impact pile driving. As the focus is on the response in the far field, where deformations are relatively small, a linear elastic constitutive behavior is assumed for the soil. The free field vibrations are calculated by means of a coupled FE–BE model using a subdomain formulation. The results show that, in the near field, the response of the soil is dominated by a vertically polarized shear wave, whereas in the far field, Rayleigh waves dominate the ground vibration and body waves are importantly attenuated. Finally, the computed ground vibrations are compared with the results of field measurements reported in the literature.     

钻孔灌注桩后压浆技术在某工程中的应用

为了提高钻孔灌注桩的单桩承载力,减少桩基沉降,可采用桩底后压浆技术工艺.结合宁波地区的地质条件和工程实例,详细介绍了后压浆钻孔桩施工工艺,并对注浆和不注浆的钻孔灌注桩单桩承载力进行了对比试验.结果表明：注浆后单桩承载力提高了22%-29.4%,具有较好的经济效益.